Locking Screw Insertion Path Guidance System in Minimally Invasive Fracture Reduction Surgery

In this paper, we propose a system to detect the location and direction of locking screw insertion using only a fluoroscopic image and guide screw insertion path, with a device that combines a SCARA robot arm and a conical remote center-of-motion (RCM) mechanism. In the proposed system, the target location and direction for screw insertion were derived from the fluoroscopic image of an intramedullary nail. The insertion guidance device comprise the SCARA robot arm and the RCM mechanism. The insertion guidance device calculated the current indicated path through forward kinematics analysis, and the target path and the current path were transmitted to the orthopedic surgeon through the control program. Moreover, the insertion guidance device set the insertion position and direction independently. The orthopedic surgeon first adjusted the SCARA robot arm to match the insertion position value to the target value and then sequentially adjusted the RCM mechanism so that the insertion direction matched the target value. After determining the insertion position and direction, the orthopedic surgeon inserted the surgical instrument through the path guided by the insertion guidance device and fastened the screw to the bone fragments and the intramedullary nail. When the proposed screw insertion guidance system was applied to fracture surgery, the locking screw was fastened with a minimum number fluoroscopic image, thus reducing surgery time and radiation exposure. The validity of the proposed method was confirmed through simulations and experiments using a fracture model.